2023-08-25 09:18:47
More than half a century ago, in 1958, the American physicist James Van Allen discovered that the planet Earth was surrounded by ions and electrons trapped in the Earth’s magnetic field and interfering with the communications of space probes.
Almost simultaneously, they were observed radiation belts of this type, but giants, around the planet Jupiter, from bursts detected in radio observations. They have now been discovered for the first time outside the solar system and described in detail (regarding studies above), which shows the universality of this structure.
The donut-shaped radiation belt of the brown dwarf LSR J1835 is a scaled-up version of those that appear on Earth and Jupiter
Specifically, in the brown dwarf LSR J1835+3259around which a team of scientists from the University of Valencia (UV) detected last January a radiation belt made up of particles charged with energy and trapped in its intense magnetic field.
The study, in which researchers from the Institute of Astrophysics of Andalusia (IAA-CSIC), the Royal Academy of Exact, Physical and Natural Sciences of Spain (RAC) and the Donostia International Physics Center (DIPC) are also participating, is now published in Magazine Science.
Brown dwarfs, along with very low mass stars, make up the astronomical category of the ultracool dwarfsand in the case of LSR J1835, the donut shape of its radiation belt is almost a scaled version of the familiar van allen belts –named after their discoverer– that appear on our planet and on Jupiter.
“Although different in size and energy, this similarity is evident when looking at the radiation belts of Jupiter and LSRJ1835 side by side,” says lead author, Juan Bautista ClementUV astronomer also linked to the International University of Valencia.
“The diameter of the magnetic structure around this ultracold dwarf is ten times greater than that of Jupiter and millions of times more powerful,” he adds. In reality, LSRJ1835 is 60 times heavier than this gas giant and spins three times as fast. Both facts combine to create an intense magnetic field on its surface, very similar to that irradiated in a magnetic resonance device.
The magnetic structure around this ultracold dwarf is ten times larger than that of Jupiter and millions of times more powerful.
Juan Bautista Climent (UV)
The new radiation belt of LSRJ1835 has been observed at radio wavelengths thanks to the European network of very long baseline interferometry (VLBI). LSRJ1835 is a brown dwarf, a transition body between a star and a planet, located 18 light years away. Therefore, it is extremely small and only the use of instruments of this type allows a detailed vision of its environment.
A global network of radio antennas allows the object to be observed with a resolution 50 times better than that of the James Webb telescope.
To image its radiation belt, the European VLBI network combined giant radio antennas spread across the globe, from Spain to China, Sweden to South Africa.
They have all scanned the brown dwarf simultaneously to achieve a resolution 50 times better than that of the James Webb Space Telescope.
very luminescent auroras
The extraordinary detail of the radio image of LSRJ1830 has also unlocked more secrets about the object. The study finds that, just like on Earth and Jupiter, the radiation belt contributes to the formation of auroras.
However, the gigantic radiation belt of LSRJ1835 gives rise to extrasolar auroras of a energy so great that become something more than an affable luminescence.
“These auroras release energy in a very concentrated manner and at very high temperatures that produce radio emission peaks 10 times greater than the total emission of LSRJ1835,” says the co-author. Jose Carlos GuiradoProfessor of Astronomy at the UV.
Both the aurora and the radiation belt can be observed simultaneously, providing valuable information about the geometry of the brown dwarf.
“For the first time we have an image of the aurora seen in polarized light and located halfway between the two emission zones corresponding to the belt, near the surface of LSRJ1835″, adds Guirado.
Both the aurora and the radiation belt can be observed simultaneously, providing valuable information about the geometry of this brown dwarf. The study posits that radio-emitting ultracold dwarfs possess magnetic fields ordered by dipoles with morphologies and aurorae similar to those of gas giants such as Jupiter.
Reconstructed radio images of LSR J1835+3259 using the European VLBI network and explanatory schematic. The two spots correspond to the donut-shaped radiation belt seen edge-on. The contour represents the powerful polarized light originating from the aurora near the surface of the brown dwarf, located midway between the radio components of the radiation belt. / Joan Climent et al./Science
On the other hand, the results of this study on LSRJ1835 demonstrate that the European VLBI network is capable of map radiation belts on nearby objectsas well as to anticipate that future instruments, such as the Square Kilometre Arraywould extend these studies to smaller and more remote objects, including exoplanets.
Knowledge of the magnetic environment of exoplanets is extremely important to gauge the possibilities of harboring extraterrestrial life. “Whether life is viable depends to a large extent on the characteristics of the radiation that surrounds these new worlds,” recalls another of the study’s authors, Miguel Angel Perez-Torresof the IAA-CSIC.
Fuente:
University of Valencia
Rights: Creative Commons.
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